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BACKGROUND/OBJECTIVES: The phase 3 REGAIN study and its open-label extension demonstrated the efficacy of the complement C5 inhibitor eculizumab in patients with treatment-refractory, acetylcholine receptor antibody-positive generalized myasthenia gravis (gMG). The aim of the ELEVATE study was to assess the effectiveness of eculizumab in clinical practice in adults with MG in the United States. METHODS: A retrospective chart review was conducted in adults with MG who initiated eculizumab treatment between October 23, 2017 and December 31, 2019. Outcomes assessed before and during eculizumab treatment using a pre- versus post-treatment study design included Myasthenia Gravis-Activities of Daily Living (MG-ADL) total scores; minimal symptom expression (MSE); physician impression of clinical change; minimal manifestation status (MMS); and concomitant medication use. RESULTS: In total, 119 patients were included in the study. A significant reduction was observed in mean MG-ADL total score, from 8.0 before eculizumab initiation to 5.4 at 3 months and to 4.7 at 24 months after eculizumab initiation (both p

The role of eculizumab in treating Shiga-toxin-producing Escherichia coli (STEC) hemolytic uremic syndrome (HUS) patients with neurological involvement remains unclear. We describe two distinctly different STEC-HUS patients with neurologic involvement successfully managed with eculizumab, and perform a literature review of all published cases. Both patients had complete resolution of neurological symptoms after initiation of eculizumab. Eighty patients with STEC-HUS treated with eculizumab were identified in the literature, 68.7% had complete resolution of neurological symptoms. Based on our experience and literature review, three prevailing themes were noted: 1) Early eculizumab administration optimized neurological outcomes, 2) Symptom resolution may not be immediate, neurological symptoms may initially worsen before improvement, and 3) Plasma exchange yielded no benefit. Early administration of eculizumab may reverse neurotoxicity in patients with STEC-HUS.

Background Carfilzomib, a new proteasome inhibitor indicated for patients with relapsed/refractory myeloma, has been associated with cases of thrombotic microangiopathy (CFZ-TMA). The role of variants in the complement alternative pathway and therapeutic potential of complement blockade with eculizumab remain to be determined. Methods We report 37 cases of CFZ-TMA recorded in the French reference center for TMA with their clinical characteristics, genetic analysis and outcome according to treatments. Results A trigger was identified in more than half of cases, including eight influenza and five severe acute respiratory syndrome coronavirus-2 cases. All patients presented with acute kidney injury (AKI) [KDIGO stage 3 in 31 (84%) patients] while neurological (n  = 13, 36%) and cardiac (n  = 7, 19%) damage were less frequent. ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type I repeats-13) and complement activity were normal (n  = 28 and 18 patients tested) and no pathogenic variant in the alternative complement pathway was found in 7 patients tested. TMA resolved in most (n  = 34, 94%) patients but 12 (44%) still displayed stage 3 AKI at discharge. Nineteen (51%) patients were treated with therapeutic plasma exchange, 14 (38%) patients received corticosteroids and 18 (50%) were treated with eculizumab. However, none of these treatments demonstrated a significant impact on outcomes. Conclusion This study is the largest case series of CFZ-TMA since its approval in 2012. Patients present with severe AKI and experience frequent sequelae. Complement variants and blockade therapy do not seem to play a role in the pathophysiology and prognosis of the disease. [ABSTRACT FROM AUTHOR]

Myasthenia gravis (MG) is a rare, autoimmune, neurological disorder. Most MG patients have autoantibodies against acetylcholine receptors (AChRs). Some have autoantibodies against muscle-specific tyrosine kinase (MuSK) or lipoprotein-receptor-related protein 4 (LRP4), and some are seronegative. Standard of care, which includes anti-cholinesterase drugs, thymectomy, corticosteroids (CS), and off-label use of non-steroidal immunosuppressive drugs (NSISTs), is bounded by potential side effects and limited efficacy in refractory generalized MG (gMG) patients. This highlights the need for new therapeutic approaches for MG. Eculizumab, a monoclonal antibody that inhibits the complement system, has been recently approved in Italy for refractory gMG. A panel of 11 experts met to discuss unmet therapeutic needs in the acute and chronic phases of the disease, as well as the standard of care for refractory patients. Survival was emphasized as an acute phase outcome. In the chronic phase, persistent remission and early recognition of exacerbations to prevent myasthenic crisis and respiratory failure were considered crucial. Refractory patients require treatments with fast onset of action, improved tolerability, and the ability to slow disease progression and increase life expectancy. The Panel agreed that eculizumab would presumably meet the therapeutic needs of many refractory gMG patients. The panel concluded that the unmet needs of current standard of care treatments for gMG are significant. Evaluating new therapeutic options accurately is essential to find the best balance between efficacy and tolerability for each patient. Collecting real-world data on novel molecules in routine clinical practice is necessary to address unmet needs. [ABSTRACT FROM AUTHOR]

Background: Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy. Genetic defects in the alternative complement (AP) pathway have been identified in 60–70% of individuals. Eculizumab is recommended as a first-line therapy. Methods: We collected the clinical data of a pediatric patient with aHUS accompanied by protein-losing enteropathy (PLE). Genetic testing was performed. Related literature on aHUS combined with PLE was reviewed. Results: A 15-year-old Chinese girl was diagnosed with aHUS at 3.7 years of age and experienced five episodes; her symptoms completely resolved with plasma treatment. Severe gastrointestinal symptoms and hypoalbuminemia presented after the first episode, and PLE was diagnosed. A novel homozygous CD46 variant was identified, and FACS revealed significantly decreased CD46 expression. She presented at a recent relapse with persistent GI symptoms and headache and progressed to chronic kidney failure; peritoneal dialysis was initiated. Eculizumab was given 8 months after the last recurrence. Surprisingly, PLE was cured. Afterward, dialysis was discontinued, and eGFR recovered to 44.8 ml/min/1.73 m2. A review of the literature indicated that PLE with thrombosis was caused by CD55 variants via hyperactivation of the AP system. We report an aHUS patient with PLE caused by CD46 variants. Symptoms of both PLE and aHUS were significantly alleviated in our patient and patients with CD55 variants treated with eculizumab, indicating that PLE was a new symptom of aHUS in our patient with a CD46 variant. Conclusions: Our case expands the phenotype of aHUS caused by a CD46 mutation and provides evidence of the efficacy of eculizumab after a long phase of chronic kidney failure. [ABSTRACT FROM AUTHOR]

Introduction: This study used network meta-analysis (NMA) to inform and compare the number needed to treat (NNT), number needed to harm (NNH), and cost per improved outcome (CPIO) associated with more recently approved treatments for anti-acetylcholine receptor antibody-positive (anti-AChR Ab+) generalized myasthenia gravis (gMG). Methods: Clinical trials of neonatal Fc receptor (FcRn) inhibitors, efgartigimod intravenous (IV) and rozanolixizumab, and complement inhibitors, ravulizumab and zilucoplan, versus placebo (with background conventional treatment) were included in the primary NMA to compare efficacy and safety outcomes. The outputs from the NMAs were used to estimate NNT and NNH of each treatment versus placebo. CPIO (2024 USD) was estimated for a ≥ 3- or ≥ 5-point reduction from baseline in Quantitative Myasthenia Gravis (QMG) and Myasthenia Gravis-Activities of Daily Living (MG-ADL) scores. Sensitivity analyses were performed adding efgartigimod PH20 subcutaneous (SC) and eculizumab to the NMA. Results: Efgartigimod IV had the lowest NNT versus placebo for achieving a ≥ 3- and ≥ 5-point reduction in QMG, as well as a ≥ 5-point reduction in MG-ADL, whereas rozanolixizumab had the lowest NNT for a ≥ 3-point reduction in MG-ADL. The NNH versus placebo was similar across comparator treatments. Efgartigimod IV had the lowest CPIO among all treatments for all assessed efficacy outcomes. Sensitivity analyses yielded results consistent with primary analysis and indicated that efgartigimod PH20 SC had comparable NNT and CPIO values to efgartigimod IV, whereas eculizumab had comparable NNT and higher CPIO values compared to other complement inhibitors. Conclusions: FcRn inhibitors and complement inhibitors assessed in this study all demonstrated clinical benefit in terms of NNT as well as an acceptable safety profile in terms of NNH. Within the limitations of this meta-analysis, efgartigimod was associated with a favorable benefit–risk profile as well as a better economic value compared to ravulizumab, rozanolixizumab, and zilucoplan as treatments for anti-AChR Ab+ gMG. [ABSTRACT FROM AUTHOR]

Paroxysmal Nocturnal Hemoglobinuria (PNH) constitutes a rare bone marrow failure syndrome characterized by hemolytic anemia, thrombotic events (TEs), and bone marrow aplasia of variable degrees. Thrombosis is one of the major clinical manifestations of the disease, affecting up to 40% of individuals with PNH. Venous thrombosis is more prevalent, affecting mainly unusual sites, such as intrabdominal and hepatic veins. TEs might be the first clinical manifestation of PNH. Complement activation, endothelial dysfunction, hemolysis, impaired bioavailability of nitric oxide, and activation of platelets and neutrophils are implicated in the pathogenesis of TEs in PNH patients. Moreover, a vicious cycle involving the coagulation cascade, complement system, and inflammation cytokines, such as interleukin-6, is established. Complement inhibitors, such as eculizumab and ravulizumab (C5 inhibitors), have revolutionized the care of patients with PNH. C5 inhibitors should be initiated in patients with PNH and thrombosis, while they constitute a great prophylactic measure for TEs in those individuals. Anticoagulants, such as warfarin and low-molecular-weight heparin, and, in selected cases, direct oral anticoagulants (DOACs) should be used in combination with C5 inhibitors in patients who develop TEs. Novel complement inhibitors are considered an alternative treatment option, especially for those who develop extravascular or breakthrough hemolysis when terminal inhibitors are administered. [ABSTRACT FROM AUTHOR]

Background: Rituximab (RTX) and eculizumab (ECU) are treatment options for refractory myasthenia gravis (MG), but comparative clinical data derived from real‐world experience are limited. Here, we describe the baseline characteristics, treatment, and safety outcomes of patients with antiacetylcholine receptor antibody‐positive (AChR+) generalized myasthenia gravis (gMG) treated with ECU and/or RTX in our clinic. Methods: Patients with refractory AChR+ gMG who received ECU or/and RTX treatment for more than 1 year at the Department of Neurology, Istanbul Faculty of Medicine were included in this observational study. After obtaining written patient consent, data were collected retrospectively from medical records. Results: Twelve patients treated with ECU and 25 patients treated with RTX were included in the analysis. Groups were comparable with regard to demographic and clinical characteristics, including age at onset of MG, disease duration, and history of thymoma. ECU was associated with significantly better outcomes compared with RTX, as measured by decreases in the mean MG activities of daily living score at 1 (p = 0.024), 3 (p < 0.001), 6 (p < 0.001), and 12 (p < 0.001) months of treatment; steroid‐sparing effect after 1 year of treatment (decrease in mean [standard deviation] daily prednisolone dose of −21.8 mg [13.5] vs. −6.6 mg [9.4] with RTX; p < 0.001); and need for rescue treatment and number of myasthenic crisis episodes during treatment (p < 0.001). No new safety signals were observed with either treatment. Conclusion: Our data provide real‐world evidence supporting ECU over RTX to treat patients with refractory AChR+ gMG. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives Methods Results Conclusions To evaluate the tolerability of crovalimab versus eculizumab in C5 inhibitor (C5i)‐naive and ‐experienced patients with PNH from COMMODORE 2, 3 and 1 (NCT04434092, NCT04654468 and NCT04432584).Pooled safety data were assessed in the total crovalimab and eculizumab populations and by C5i‐naive versus C5i‐switched status in patients receiving crovalimab. Analyses include 6.5 months of additional follow‐up from the COMMODORE 2 and 1 primary analyses.COMMODORE safety data (crovalimab, 393 patients [naive, 192 patients; switched, 201 patients]; eculizumab, 111 patients) were analysed. The total patient years (PY) were 503.9 and 51.1 in the total crovalimab and eculizumab populations, respectively, with 471 and 581 adverse events (AEs) per 100 PY. Serious infection rates were 8.9 and 13.7 AEs per 100 PY, respectively; no meningococcal infections were reported. Fatal AEs occurred in eight (2%) patients receiving crovalimab (naive, six patients; switched, two patients) and one (1%) receiving eculizumab, all treatment unrelated. In C5i‐switched patients, 39 (19%) had transient immune complex reactions (risk when switching between C5i and crovalimab); the majority were Grades 1–2 arthralgia and rash, and 16 (8%) had Grade 3 events.Crovalimab's safety profile was consistent with eculizumab's and was generally comparable between C5i‐naive and C5i‐switched patients. [ABSTRACT FROM AUTHOR]

Introduction: ABO-incompatible (ABOi) kidney transplantation (KT) has become an important option to overcome organ shortage. Plasmapheresis/rituximab-based desensitization therapy has successfully reduced anti-ABO antibody levels and suppressed antibody-mediated rejection (AMR) in ABOi KT. However, high titers of anti-ABO antibodies in some patients are refractory to standard desensitization, leading to loss of KT opportunities or AMR. Methods: Eculizumab treatment was used an adjunctive therapy to rescue high-titer ABOi KT patients refractory to plasmapheresis/rituximab-based desensitization. Molecular phenotypes of allograft biopsies and cellular phenotypes of peripheral blood mononuclear cells of eculizumab group were compared with those of control groups using the Banff Human Organ Transplant gene panel and flow-cytometric analysis, respectively. Results: The initial titers of anti-ABO antibodies in the two patients were 1:512 and >1:1024; the final pre-transplant titers after desensitization were 1:128 and 1:64. Both patients received eculizumab from KT day to two or four weeks post-KT and maintained stable renal function up to one-year post-transplantation without overt infection, despite early episodes of probable AMR or borderline T cell-mediated rejection. Molecular phenotype analysis revealed that gene expression patterns in the ABOi KT with eculizumab group overlapped with those in the ABOi KT with AMR group more than in the ABOi KT without AMR group, except for complement pathway-related gene expression. Anti-ABO antibody titers decreased to low levels 1–3 months post-transplant in the eculizumab group in parallel with decreasing anti-B-specific B cells. Conclusions: Short-term eculizumab therapy is promising for rescuing ABOi KT recipients with high anti-ABO antibody titers refractory to plasmapheresis-based desensitization therapy. [ABSTRACT FROM AUTHOR]

Key Clinical Message: This unique case of generalized myasthenia gravis shows sustained stability of a patient's condition for 3 years with eculizumab/ravulizumab treatment following 16 years of refractory disease. It highlights the long‐term effectiveness of C5 inhibitors in a real‐world setting, aiding physicians in their decision‐making for refractory cases and treatment discontinuation scenarios. [ABSTRACT FROM AUTHOR]

Objectives: neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disease mainly affecting optic nerves and the spinal cord. Due to the potentially irreversible tissue damage, prevention of relapses is of utmost importance. Methods: We describe the atypical clinical course and pathology results of a patient with anti-aquaporin-4 antibody (anti-AQP4-Ab)-associated NMOSD who developed aseptic meningitis followed by limbic-encephalitis-like presentation with extensive brain lesions upon treatment with rituximab and tocilizumab. Results: The patient developed subacute cognitive decline with magnetic resonance imaging (MRI) evidence of extensive brain white matter lesions. In the hypothesis of an opportunistic brain infection, she underwent brain biopsy of the temporal pole. Pathology results revealed typical NMOSD findings with complement activation, supporting the hypothesis of an atypical presentation of anti-AQP-Ab-associated NMOSD. Accordingly, treatment with the complement-targeting drug eculizumab was started, leading to a dramatic clinical and MRI improvement. Discussion: aseptic meningitis and limbic encephalitis could represent a rare phenotype of anti-AQP4-Ab-associated NMOSD. [ABSTRACT FROM AUTHOR]

Acute myeloid leukemia (AML) has not been identified as a cause of secondary hemolytic–uremic syndrome (HUS). This case report describes a woman who developed severe HUS at the time of AML diagnosis and responded favorably to initial treatment with eculizumab, which stabilized her condition and allowed for treatment of the AML. After one year, with stable renal function and genetic studies reported as normal, eculizumab was successfully discontinued. The prompt use of eculizumab was critical to the patient's survival and improvement in renal function, highlighting the efficacy of early eculizumab treatment in secondary HUS. [ABSTRACT FROM AUTHOR]

The advent of recycling antibodies, leveraging pH-dependent antigen binding and optimized FcRn interaction, has advanced the field of antibody therapies, enabling extended durability and reduced dosages. Eculizumab (Soliris®) demonstrated the efficacy of C5 inhibitors for paroxysmal nocturnal hemoglobinuria (PNH), while its derivative, ravulizumab (Ultomiris®), recognized as a recycling antibody, extended the dosing intervals. However, limitations including intravenous administration and inefficacy in patients with the R885H single-nucleotide polymorphism (SNP) in C5 could necessitate alternative solutions. Crovalimab (PiaSky®), a next-generation recycling antibody, overcomes these challenges with innovative charge engineering, achieving the enhanced cellular uptake of C5–crovalimab complexes and targeting a unique C5 epitope, allowing for efficacy regardless of the R885H SNP. This study highlights crovalimab's distinctive molecular features, showing its eliminated binding to Fcγ receptors and C1q, alongside its optimized antigen binding characteristics. The impact of charge engineering was reconfirmed in mice, demonstrating faster C5 clearance than recycling antibodies. Notably, in the maintenance dosing regimen, crovalimab neutralizes approximately seven C5 molecules per antibody on average. Furthermore, its design also reduces the viscosity to facilitate high-concentration formulations suitable for subcutaneous delivery. Consequently, crovalimab offers a four-weekly subcutaneous injection regimen for PNH, marking a substantial improvement in treatment convenience and potentially transforming patients' quality of life. [ABSTRACT FROM AUTHOR]

The complement system is a set of over 50 proteins that constitutes an essential part of the innate immune system. Complement system activation involves an organized proteolytic cascade. Overactivation of complement system activation is the main pathogenic mechanism of several diseases and contributes to the manifestations of many other conditions. This review describes the normal complement system and the role for complement dysregulation in critical illnesses, notably sepsis and acute respiratory distress syndrome. Complement activation is involved in the immune system response to pathogens but, when excessive, can contribute to tissue damage, runaway inflammation, and capillary leakage syndrome. Complement overactivation may play a key role in severe forms of coronavirus disease 2019 (COVID-19). Two diseases whose manifestations are mainly caused by complement overactivation, namely, atypical hemolytic and uremic syndrome (aHUS) and myasthenia gravis, are discussed. A diagnostic algorithm for aHUS is provided. Early complement-inhibiting therapy has been proven effective. When renal transplantation is required, complement-inhibiting drugs can be used prophylactically to prevent aHUS recurrence. Similarly, acetylcholine-receptor autoantibody-positive generalized myasthenia gravis involves complement system overactivation and responds to complement inhibition. The two main complement inhibitors used in to date routine are eculizumab and ravulizumab. The main adverse event is Neisseria infection, which is rare and preventable, but can be fatal. The complement system is crucial to health but, when overactivated, can cause or contribute to disease. Effective complement inhibitors are now available, although additional data are required to determine optimal regimens. Further research is also needed to better understand the complement system, develop advanced diagnostic tools, and identify markers that allow the personalization of treatment strategies. [ABSTRACT FROM AUTHOR]

Purpose: Atypical hemolytic uremic syndrome (aHUS) is a rare progressive thrombotic microangiopathy caused by overactivation in the alternative complement pathway. A wide spectrum of environmental triggers, such as viruses, vaccination, drugs, pregnancy, neoplasms, transplant, and autoimmune diseases can cause aHUS in genetically susceptible individuals. In this report, the diagnosis and treatment process of aHUS and bilateral retinal venous occlusion (RVO) will be presented. Methods: Single-case, retrospective management of ophthalmological and systemic manifestations. Results: A 28-year-old G2P2 female with acute blurred vision and history of acute renal failure. She was diagnosed with preeclampsia in her gestation history. After the laboratory work-up, the diagnosis of aHUS was confirmed. She was treated with eculizumab following 14 days of plasmapheresis. However, her visual acuity was 20/20 on the right and 20/60 on the left at the time of admission. Retinal examination revealed flame-shaped hemorrhages, exudation, and macular edema. The patient was diagnosed with branch RVO in the right eye. Subsequently, central RVO was occurred in the left eye. Intravitreal dexamethasone implant was administered for both eyes since there was no reasonable regression in retinal findings with bevacizumab treatment. She went into remission and her BCVA reached 20/25 during the 12-month follow-up period under the eculizumab therapy. Conclusion: Diagnosis of aHUS is challenging especially during pregnancy and the postpartum period. Although ocular involvement is quite rare, we described bilateral RVO in aHUS case with homozygous nonsense mutation (c.2134 G > T p.G712). Dexamethasone implant should be considered for the treatment of RVO in aHUS cases. [ABSTRACT FROM AUTHOR]

Background The event of extradural hematoma in the absence of head trauma is a rare central nervous system complication of sickle cell disease. We report here a case of spontaneous extradural hematoma in a patient being treated for sickle cell vasoocclusive crisis complicated by hyperinflammation and thrombotic microangiopathy. The significance of inflammation as an integral component of the pathomechanism of vasoocclusive crisis in patients with sickle cell disease and the role of heme in activating the complement system's alternative pathway are highlighted in this case report. Case Presentation A teenage patient with sickle cell disease developed a spontaneous right parietal extradural hematoma while receiving treatment for sickle cell vasoocclusive crisis. The concurrent events of hyperinflammation, disseminated intravascular coagulation, hyperhemolysis syndrome, thrombotic microangiopathy, and refractory postoperative bleeding complicated this patient's clinical course after surgical evacuation of extradural hematoma. This patient was subsequently treated with eculizumab and improved in the days following. Conclusion Treatment with the anti-C5 monoclonal antibody eculizumab, which targets and inhibits terminal complement system activation, reversed the deleterious cascade of events in this patient with sickle cell disease. [ABSTRACT FROM AUTHOR]

Background: Between 5 and 50% of atypical hemolytic uremic syndrome (aHUS) cases in children are caused by autoantibodies against complement factor H (CFH). Given the acquired autoimmune nature of the disease, plasma exchange (PE) and various immunosuppressive treatments have been used. More recently, eculizumab has been proposed. Methods: In this multicenter, retrospective study, we report outcomes of 12 children with anti-FH antibody-associated HUS treated with eculizumab associated with various immunosuppressive regimens. Results: Patients were treated with eculizumab for 15.5 [9.5;23.0] months and 3 received PE or IgG adsorption. Three patients received mycophenolate mofetil (MMF) alone, 1 patient received MMF and steroids, 1 patient received MMF and rituximab, 3 patients received MMF/steroids and rituximab, and 4 patients did not receive any immunosuppression. Anti-FH antibody levels significantly decreased but no difference was observed based on the immunosuppressive regimen. Eculizumab was discontinued in 7/10 patients after 11 [7.5;15.5] months and MMF in 6/8 patients after 36 [35;40] months. Anti-FH titers at MMF discontinuation ranged from 257 to 3425 UI/L. None of these patients relapsed and eGFR at last follow-up was above 70 mL/min/1.73 m2 in all patients. Conclusions: Eculizumab is effective and safe in inducing and maintaining remission in aHUS secondary to anti-FH antibodies and renders reduction of anti-FH titers less urgent. Anti-FH antibody titers decreased in most patients irrespective of the immunosuppressive treatment chosen, so that a strategy consisting of combining eculizumab with MMF monotherapy seems sufficient at least in non-Indian or less severe forms of anti-FH antibody-associated HUS. [ABSTRACT FROM AUTHOR]

Copyright of Neurologie Pro Praxi is the property of SOLEN sro and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The complement cascade is an ancient and highly conserved arm of the immune system. The accumulating evidence highlights elevated activity of the complement cascade in cancer microenvironment and emphasizes its effects on the immune, cancer, and cancer stroma cells, pointing to a role in inflammation-mediated etiology of neoplasms. The role the cascade plays in development, progression, and relapse of solid tumors is increasingly recognized, however its role in hematological malignancies, especially those of myeloid origin, has not been thoroughly assessed and remains obscure. As the role of inflammation and autoimmunity in development of myeloid malignancies is becoming recognized, in this review we focus on summarizing the links that have been identified so far for complement cascade involvement in the pathobiology of myeloid malignancies. Complement deficiencies are primary immunodeficiencies that cause an array of clinical outcomes including an increased risk of a range of infectious as well as local or systemic inflammatory and thrombotic conditions. Here, we discuss the impact that deficiencies in complement cascade initiators, mid- and terminal-components and inhibitors have on the biology of myeloid neoplasms. The emergent conclusions indicate that the links between complement cascade, inflammatory signaling, and the homeostasis of hematopoietic system exist, and efforts should continue to detail the mechanistic involvement of complement cascade in the development and progression of myeloid cancers. [ABSTRACT FROM AUTHOR]

We describe initial, current, and future aspects of complement activation and inhibition in the rare hematological disease paroxysmal nocturnal hemoglobinuria (PNH). PNH is a rare but severe hematological disorder characterized by complement‐mediated intravascular hemolysis resulting in anemia and severe thrombosis. Insights into the complement‐mediated pathophysiology ultimately led to regulatory approval of the first‐in‐class complement inhibitor, eculizumab, in 2007. This anti‐complement C5 therapy resulted in the stabilization of many hematologic parameters and dramatically reduced the often fatal, coagulant‐resistant thrombotic events. Despite the remarkable clinical success, a substantial proportion of PNH patients experience suboptimal clinical responses during anti‐C5 therapy. We describe the identification and mechanistic dissection of four unexpected processes responsible for such suboptimal clinical responses: (1) pharmacokinetic and (2) pharmacodynamic intravascular breakthrough hemolysis, (3) continuing low‐level residual intravascular hemolysis, and (4) extravascular hemolysis. Novel complement therapeutics mainly targeting different complement proteins proximal in the cascade attempt to address these remaining problems. With five approved complement inhibitors in the clinic and many more being evaluated in clinical trials, PNH remains one of the complement diseases with the highest intensity of clinical research. Mechanistically unexpected breakthrough events occur not only with C5 inhibitors but also with proximal pathway inhibitors, which require further mechanistic elaboration. [ABSTRACT FROM AUTHOR]

Aim: An excessively activated or dysregulated complement system has been proven to be a vital contributor to the pathogenesis of periodontitis. It has been previously hypothesized that inhibiting the activity of complement component C5 by targeting the C5a receptor is a powerful candidate for treating periodontitis. Here, we apply the drug target instrumental variable (IV) approach to investigate the therapeutic effect of genetically proxied inhibition of C5 on periodontitis. Method: In our primary analysis, we used 26 independent 'cis' single nucleotide polymorphisms as IVs from the vicinity of the encoding locus of C5 that are associated with plasma C5 levels. In a secondary analysis, we assess the validity of our primary findings, exploring the involvement of alternative downstream biomarkers, interleukin 17 (IL-17), interleukin 1b (IL-1b), and tumor necrosis factor (TNF). Summary statistics of plasma levels (C5, IL-17, IL-1b, and TNF) were obtained from a genome-wide association study (GWAS) of 35,559 European descent individuals. We extracted association statistics from a GWAS of 17,353 clinical periodontitis cases and 28,210 European controls. Wald ratios were combined using inverse-variance weighted meta-analysis. Results: In our primary approach, inhibiting C5 reduced the risk of periodontitis (Odds ratio 0.89 per 1 standard deviation reduction in C5; 95% confidence Interval 0.80-0.98, p value=0.022). Our secondary analysis suggests an involvement of IL-17 within the potential causal pathway, but was inconclusive for other biomarkers. Conclusions: The findings from our study suggest that C5 inhibition may reduce the risk of periodontitis, prioritizing C5 inhibitors as a potential adjunctive therapeutic intervention in this disease. [ABSTRACT FROM AUTHOR]

This case report describes the clinical course of a patient with relapsed IgA kappa multiple myeloma with high-risk cytogenetics. Initially treated with daratumumab–bortezomib–lenalidomide–dexamethasone (Dara-VRD) then transitioned to lenalidomide maintenance. However, he experienced a relapse and was treated with carfilzomib-based therapy (CFZ) but developed drug-induced thrombotic microangiopathy (DI-TMA). Despite receiving eculizumab and supportive care, the patient's condition worsened, leading to encephalopathy and refractory gastrointestinal bleeding in the setting of persistent thrombocytopenia. Ultimately, the decision was made to transition to comfort-focused care. DI-TMA has been documented with various proteasome inhibitors such as ixazomib and bortezomib. Additionally, other medications such as cyclosporine, tacrolimus, clopidogrel, ticlopidine, and interferon have been associated with DI-TMA as well (Pisoni et al. (Drug Saf 24:491–501, 2001) [18]). Here we discuss a case of carfilzomib-induced TMA (CFZ-TMA) refractory to eculizumab as well as a review of the published literature. [ABSTRACT FROM AUTHOR]

Thrombotic microangiopathy (TMA) is defined by the typical triad of severe thrombocytopenia, hemolytic anemia and endorgan dysfunction and can be characterized by the pathophysiology of ischemia-inducing microthrombi in arterioles and capillaries possibly leading to severe organ dysfunction up to acutely life-threatening endorgan damage. In terms of etiology, management, therapy and prognosis, the following manifestations are distinguished: thrombotic thrombocytopenic purpura (TTP), shigatoxin-induced hemolytic-uremic syndrome (STEC-HUS), secondary comorbidity-related TMA and atypical hemolytic-uremic syndrome (aHUS). We present the case of a 49 year old lung transplant recipient developing aHUS. The complexity of the underlying pathomechanisms of TMA, the complicated differentiation of each TMA manifestation and the complex management of aHUS in the post-transplant setting illustrate the uniqueness of this patient case. [ABSTRACT FROM AUTHOR]

Systemic lupus erythematosus (SLE) can present with a diverse array of hematologic manifestations, among which atypical hemolytic uremic syndrome (aHUS) is a rare entity. SLE-triggered aHUS has significant morbidity and mortality without timely intervention, yet its frequency remains uncertain and optimal strategies for complement-directed therapies are largely expert-driven. We performed a comprehensive literature review and present a case of a 23-year-old female newly diagnosed with SLE/class IV lupus nephritis who developed aHUS that rapidly responded to the C5 antagonist, eculizumab. Review of the current literature identified forty-nine published cases of SLE with concurrent aHUS and revealed a predilection for aHUS in younger SLE patients, concurrent presentation with lupus nephritis, anti-dsDNA positivity, and complement system abnormalities. Over seventy percent of cases used eculizumab as complement-directed therapy with a trend towards faster time to improvement in laboratory parameters, though reported outcomes were highly variable. Early recognition of aHUS in SLE is pivotal in guiding appropriate therapeutic interventions, and prompt initiation of eculizumab may reduce the potential morbidity associated with plasmapheresis and additional immunosuppression. While eculizumab showcases promising results, its optimal timing and duration remain elusive. An understanding of a patients' complement genetics could aid management strategies, and ongoing research into complement-targeted therapies offers promising avenues for both SLE and aHUS treatment. [ABSTRACT FROM AUTHOR]

Background/Objectives: Eculizumab is a first-line treatment for atypical hemolytic uremic syndrome (aHUS), and patients undergoing eculizumab therapy may become more susceptible to infection caused by Neisseria meningitidis (Nm). While meningococcal vaccination is required for patients undergoing eculizumab therapy, there is limited knowledge about meningococcal carriage in children with aHUS. We aimed to evaluate (1) the prevalence of Nm carriage, (2) serogroup distribution, and (3) the immunization status of children undergoing eculizumab treatment for aHUS. Methods: The Meningo-aHUS study is a prospective, multi-center study evaluating meningococcal carriage in children and adolescents in Türkiye receiving eculizumab for aHUS. We noted the age, gender, daycare, school, or university attendance, passive smoking status, previous infection and antibiotic use, and previous immunization history, including meningococcal vaccines, from the medical records of those children with aHUS. We collected nasopharyngeal samples, tested them for Nm using real-time polymerase chain reaction, and performed a serogroup analysis on the positive samples. Results: We collected nasopharyngeal samples from 62 children with aHUS. Out of 62 children, 61 (98.4%) had received at least one dose of the meningococcal vaccine. The median time since the last meningococcal vaccine dose was 15 months (1–59 months). We detected meningococcal carriage in three (4.8%, 95% CI 1.0–13.5) children, and all three strains were non-groupable (NG). No other serogroups were detected. Conclusions: Almost all the children received their risk-group meningococcal immunization, including booster doses. A 4.8% of children with aHUS carried NG meningococci and, no vaccine serogroups were detected. Patients treated with eculizumab remain profoundly susceptible to IMD due to these NG meningococcal strains. The occurrence of breakthrough cases and carriage of Nm, especially NG strains, highlights the significance of maintaining a state of constant alertness, promptly seeking medical attention, and swiftly treating any symptoms that align with IMD, regardless of their vaccination status or antibiotic prophylaxis. [ABSTRACT FROM AUTHOR]

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Abstract Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematological disorder characterized by the absence of complement regulatory proteins on the surface of erythrocytes, leading to intravascular hemolysis and thrombosis. Managing PNH during pregnancy poses significant challenges due to increased risks of morbidity and mortality. This case report describes the detailed obstetric course of a 44‐year‐old woman with PNH and additional hereditary protein C deficiency who had previously experienced multiple thrombotic events and adverse pregnancy outcomes (two early miscarriages and one stillbirth at 25 weeks gestation [WG]), treated with eculizumab (terminal C5 inhibitor) and optimal anticoagulation management. Close monitoring of hemolysis and hemostasis parameters was conducted throughout the gestation period together with increased obstetrical surveillance. The pregnancy progressed without thrombotic complications or breakthrough hemolysis, and the patient delivered a healthy newborn at 36 WG after induction of labor due to restricted fetal growth. To the best of our knowledge, this is the first reported case of a positive pregnancy outcome despite PNH in conjunction with hereditary thrombophilia. This case report highlights the importance of a multidisciplinary approach involving hematologists and obstetricians in the management of pregnant women with PNH. Tailored therapy, close monitoring, and comprehensive care are crucial to minimize risks and optimize outcomes.

Abstract Atypical haemolytic uremic syndrome (aHUS) is a rare disorder characterised by complement-mediated thrombotic microangiopathy (TMA). Despite clinical guidelines, the diagnosis and treatment of aHUS in its early stages remains challenging. This study examined the annual trends in aHUS clinical practices in Japan and explored factors influencing early diagnosis and treatment. Using data from the 2011–2020 Diagnosis Procedure Combination database, 3096 cases with the HUS disease code were identified, of which 217 were confirmed as aHUS and treated with eculizumab or plasma exchange. Early initiation, defined as starting eculizumab or plasma exchange within 7 days of admission, was the focus of the study. Our study revealed no significant changes over time in the number of aHUS diagnoses, cases treated with eculizumab, or early initiation cases. Early initiation cases underwent haemodialysis earlier and had ADAMTS13 activity measured earlier, shorter hospital stays, and lower hospitalisation costs than late initiation cases. In conclusion, we found no increase in the number of newly diagnosed aHUS cases or early treatment initiation over time. Early recognition of TMA and differentiation of the causative disease are crucial for identifying potential aHUS cases, which may lead to better patient prognoses.

Catastrophic antiphospholipid syndrome (CAPS) is a life-threatening condition of small-vessel thrombosis with acute multiple-organ involvement and visceral damage. In this report, we present a case of a patient with CAPS who is refractory to conventional therapy. For the first time in a patient with CAPS, marked C5b-9 formation was demonstrated on microvascular endothelial cells, suggesting the usefulness of therapeutic complement inhibition in this setting. Eculizumab, a C5-blocking monoclonal antibody, is remarkably effective in the treatment of different forms of thrombotic microangiopathy by controlling complement system hyperactivation. It halted the "thrombotic storm" and promptly achieved full recovery of thrombocytopenia. However, kidney function did not recover, possibly because eculizumabwas administered too late. Conceivably, the timing of treatment is crucial to achieving disease remission before irreversible structural damage occurs in target organs, thereby preventing their complete functional recovery. [ABSTRACT FROM AUTHOR]